Reliable microstrip routing for electronics components

ABSTRACT

Reliable microstrip routing arrangements for electronics components are described. In an example, a semiconductor apparatus includes a semiconductor die having a surface with an integrated circuit thereon coupled to contact pads of an uppermost metallization layer of a semiconductor package substrate by a plurality of conductive contacts. A plurality of discrete metal planes is disposed at the uppermost metallization layer of the semiconductor package substrate, each metal plane located, from a plan view perspective, at a corner of a perimeter of the semiconductor die. Microstrip routing is disposed at the uppermost metallization layer of the semiconductor package substrate, from the plan view perspective, outside of the perimeter of the semiconductor die.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/930,086, filed on Jun. 28, 2013, the entire contents of which arehereby incorporated by reference herein.

TECHNICAL FIELD

Embodiments of the invention are in the field of semiconductor packagesand, in particular, reliable microstrip routing for electronicscomponents.

BACKGROUND

Today's consumer electronics market frequently demands complex functionsrequiring very intricate circuitry. Scaling to smaller and smallerfundamental building blocks, e.g. transistors, has enabled theincorporation of even more intricate circuitry on a single die with eachprogressive generation. Semiconductor packages are used for protectingan integrated circuit (IC) chip or die, and also to provide the die withan electrical interface to external circuitry. With the increasingdemand for smaller electronic devices, semiconductor packages aredesigned to be even more compact and must support larger circuitdensity. Furthermore, the demand for higher performance devices resultsin a need for an improved semiconductor package that enables a thinpackaging profile and low overall warpage compatible with subsequentassembly processing.

Controlled Collapse Chip Connections (C4) solder ball connections havebeen used for many years to provide flip chip interconnections betweensemiconductor devices and substrates. A flip chip or C4 interconnectionis a type of mounting used for semiconductor devices, such as integratedcircuit (IC) chips, MEMS or components, which utilizes solder bumpsinstead of wire bonds. The solder bumps are deposited on the C4 pads,located on the top side of the substrate package. In order to mount thesemiconductor device to the substrate, it is flipped over—the activeside facing down on the mounting area. The solder bumps are used toconnect the semiconductor device directly to the substrate. However,this approach may be limited by the size of the mounting area and maynot readily accommodate stacked die.

On the other hand, conventional wire-bonding approaches may limit thenumber of semiconductor die that can reasonably be included in a singlesemiconductor package. Furthermore, general structural issues may arisewhen attempting to package a large number of semiconductor die in asemiconductor package.

Newer packaging and die-to-die interconnect approaches, such as throughsilicon via (TSV) and silicon interposer, are gaining much attentionfrom designers for the realization of high performance Multi-Chip Module(MCM) and System in Package (SiP). However, additional improvements areneeded in the evolution of semiconductor packages and die-to-dieinterconnection approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates cross-sectional views of a stripline configurationand a microstrip configuration for transmission lines, in accordancewith the prior art.

FIG. 2 illustrates a cross-sectional view and a plan view of a packageddie having an epoxy fillet crack.

FIG. 3A illustrates a cross-sectional view of a packaged die havingmicrostrip routing and a metal plane to accommodate for an epoxy filletcrack, in accordance with an embodiment of the present invention.

FIG. 3B illustrates a plan view of a packaged die having microstriprouting and a metal plane to accommodate for an epoxy fillet crack, inaccordance with an embodiment of the present invention.

FIG. 4A illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an embedded interconnect bridge(EmIB) and including microstrip routing and a metal plane to accommodatefor an epoxy fillet crack, in accordance with an embodiment of thepresent invention.

FIG. 4B illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an embedded interconnect bridge(EmIB) and including microstrip routing and a metal plane to accommodatefor an epoxy fillet crack, in accordance with an embodiment of thepresent invention.

FIG. 5 illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an interposer and includingmicrostrip routing and a metal plane to accommodate for an epoxy filletcrack, in accordance with an embodiment of the present invention.

FIG. 6 illustrates a cross-sectional view of a 3D integrated circuitpackage with through-mold first level interconnects and includingmicrostrip routing and a metal plane to accommodate for an epoxy filletcrack, in accordance with an embodiment of the present invention.

FIG. 7 illustrates a cross-sectional view of a 3D integrated circuitpackage with through-mold first level interconnects and includingmicrostrip routing and a metal plane to accommodate for an epoxy filletcrack, in accordance with an embodiment of the present invention.

FIG. 8 is a schematic of a computer system, in accordance with anembodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reliable microstrip routing for electronics components is described. Inthe following description, numerous specific details are set forth, suchas packaging and interconnect architectures, in order to provide athorough understanding of embodiments of the present invention. It willbe apparent to one skilled in the art that embodiments of the presentinvention may be practiced without these specific details. In otherinstances, well-known features, such as specific semiconductorfabrication processes, are not described in detail in order to notunnecessarily obscure embodiments of the present invention. Furthermore,it is to be understood that the various embodiments shown in the Figuresare illustrative representations and are not necessarily drawn to scale.

One or more embodiments of the present invention are directed toapproaches for, and the resulting structures of, fabricating microstriprouting on server and other high performance products. Embodiments may,but need not, pertain to one or more of epoxy, fillet crack, microstripstructures, and stripline products.

To provide a general context, server and other high performance productshave typically incorporated stripline routing instead of microstriprouting. On reason for doing so is that stripline routing can providesuperior far-end crosstalk (FEXT) performance, e.g., reduced cross-talk,and high thermomechanical reliability. From an electrical performanceperspective, the superiority of stripline transmission lines can be dueat least in part to the phenomenon that stripline configuration cansupport a balanced wave propagation of even and odd modes leading totheoretically zero FEXT.

For the sake of providing visual context, FIG. 1 illustratescross-sectional views of a stripline configuration 100 and a microstripconfiguration 102 for transmission lines, in accordance with the priorart. Referring to FIG. 1, stripline routing 100 in a package requiresthree package layers compared to the two-layer routing topology ofmicrostrip lines 102. As such, although performance benefits have beenrealized with stripline routing 100, a stripline topology adds cost tothe overall package manufacturing and assembly.

Recently, microstrip stubby line routing has been proposed as a solutionto eliminate FEXT issues associated with package and sockettechnologies. It has been demonstrated through simulation data thatstubby microstrip lines can show an improvement of 5-10 ticks (1 tick isapproximately 12 mV) over conventional microstrip lines. However,although stubby lines can enable microstrip routing from an electricalperformance perspective, a process solution is needed to enablemicrostrip routing on server and other high performance products whilestill achieving thermomechanical reliability.

A copper (Cu) ground plane disposed on a surface layer of a package canact as a crack propagation barrier. Typically, cracks in server packagebegin at epoxy fillet corners (e.g., at a highest distance from neutralpoint (DNP)) and extend down to the solder resist and to the Cu surfacelayer in an underlying substrate. The ground Cu plane on the surfacelayer in a stripline routing can prevent crack propagation to layersunderneath and can also prevent electrical failure. In microstriprouting, however, the surface layer has Cu traces which can crack andcause opens.

A ground plane also enables a solder resist trench to limit epoxyspread. For example, server products require a substantial amount ofepoxy volume for reliability (e.g., spreading as much as approximately3-4 millimeters away from a die). The solder resist trench can aid instopping epoxy from spreading further due to sharp steps acting as asurface tension barrier. As the solder resist trench reveals Cuunderneath, microstrip routing cannot typically be enabled to avoid livetraces open to air catching dust or dirt, and causing shorts.

As an example to highlight issues with state of the art approaches, inFIG. 2, a cross-sectional view 200 and a plan view 202 of a packaged diehaving an epoxy fillet crack is illustrated. Referring to FIG. 2, a die210 is flip-chip bonded to a substrate 212. The substrate 212 includesmetal routing layers 214 and dielectric layers 216, as well as a copperplane 218. The die 210 is adhered to a solder resist 220 atop thesubstrate 212 by an epoxy fillet layer 222. A solder resist trench 224provides a keep out zone (KOZ) to limit epoxy fillet flow. The copperplane 218 can be used to stop propagation of cracks, such as epoxyfillet crack 226, that can form due to thermal stresses. That is, thecopper plane 218 in the surface layer arrests fillet crack propagationand also allows a solder resist trench to define an epoxy keep out zone.

Referring again to FIG. 2, the copper plane 218 surrounds the entireperimeter of the die 210, limiting routing 214 to regions below die 210and below the copper plane 218. Current approaches for server and otherhigh performance products involve the use of stripline routing toovercome the aforementioned risks. Process solutions enabling microstriprouting on server products, however, are needed for cots considerations,etc.

Addressing one or more of the above mentioned issues with state of theart packaging and routing options, FIGS. 3A and 3B illustrate across-sectional view and a plan view, respectively, of a packaged diehaving microstrip routing and a metal plane to accommodate for an epoxyfillet crack, in accordance with an embodiment of the present invention.

Referring to FIGS. 3A and 3B, a die 310 is flip-chip bonded to asubstrate 312, e.g., through solder balls or metal bumps 311 (such as aball grid array (BGA)). The substrate 312 includes metal routing layers314, as well as microstrip routing 315 outside of the periphery of thedie 310, and dielectric layers 216. A plurality of metal planes 318,e.g. copper planes, is also included, but each plane located only at thecorners of the die 310, with respect to the plan view. The die 310 isadhered to a solder resist 320 atop the substrate 312 by an epoxy filletlayer 322. A solder resist trench 324 provides a keep out zone (KOZ) tolimit epoxy fillet flow. The metal planes 318 can be used to stoppropagation of cracks, such as epoxy fillet crack 326, that can form dueto thermal stresses. That is, in accordance with an embodiment of thepresent invention, the metal planes 218 in the surface layer arrestfillet crack propagation.

Referring again to FIGS. 3A and 3B, in an embodiment, the metal planes318, such as copper planes, can be used to arrest corner fillet crackswithout surrounding the entire perimeter of the die 310. That is, in oneembodiment, the copper planes are discrete since they are non-continuouswith one another and are located only in the corners to arrest thecracks that typically form at a furthest distance from the center of thedie. As such, reliability of the package can be maintained. As such, inan embodiment, microstrip routing is provided in the surface layer ofthe substrate except at the die corners. As such, in one embodiment, onesubstrate layer can be reduced (on both sides), aiding in reducing ofpackage thickness substrate processing costs.

Referring again to FIGS. 3A and 3B, in an embodiment, epoxy filletspread can be arrested by a trench 324 formed partially into, but nottotally through, the solder resist mask 320. In this way, microstriprouting 315 is not exposed by the trench 324. In one such embodiment,two solder resist (SR) layers can be used together to provide astructure such as the structure illustrated in FIG. 3A. The trench 324is fabricated only in the top layer to stop epoxy spread. The second,overlying, SR layer can be processed after fully curing the first SRlayer. In another such embodiment, a second SR layer can be etched sucha way that the layer only covers the region outside of an epoxy keep outzone (KOZ). The layer can be fabricated from low surface energy materialsuch that it acts as a surface energy barrier. In yet anotherembodiment, a sharper solder resist taper angle (e.g., greater than 90degrees) is used as a surface tension barrier. Other possibilities forlimiting epoxy spread include, but are not limited to, low surfaceenergy material employed as a surface energy barrier to stop epoxy flowinstead of the use of a solder resist trench, laser etching employed topartially remove solder resist to stop epoxy, and use of a highviscosity material barrier.

In reference again to FIGS. 3A and 3B, in an embodiment, surface routingis enabled without compromising reliability or process requirements. Inone such embodiment, such approaches for surface routing are applicableto a variety of microchip packaging design and fabrication approaches.Embodiments may be detectable through visual inspection of a solderresist layer, epoxy fillet and/or surface routing in a packagesubstrate. In one embodiment, such enabling of microstrip routingprovides a significant cost reduction opportunity by reducing thepackage layer count.

Thus, one or more embodiments described herein relate to substraterouting structures in which microstrip routing is enabled whileutilizing a minimum number of layers and, possibly, without an increasein the surface area of the substrate or die. Implementations includeapplications in high performance microprocessor (e.g., server) packages,multi-chip packages, organic package substrates, transmission lines, 2.5D (Si feature between die and board), on-die, on package, etc.architectures. More generally, embodiments described herein may have farreaching implementations for CPUs/processors, multi-chip/3D packagingincluding CPU in combination with other devices, memory (e.g.,flash/DRAM/SRAM, etc. Several non-limiting examples are provided below.Application may be particularly useful for flip chip, controlledcollapse chip connection (C4) and/or ball grid array (BGA)implementations.

In a first general example, an example of which is illustrated in FIG.3, in accordance with an embodiment of the present invention, a die iscoupled to a flexible substrate or a rigid substrate, depending upon thespecific application. The substrate has a plurality of electrical tracesdisposed therein. In an embodiment, an external contact layer is alsoformed. In one embodiment, the external contact layer includes a ballgrid array (BGA). In other embodiments, the external contact layerincludes an array such as, but not limited to, a land grid array (LGA)or an array of pins (PGA). Regions for inclusion of discrete metalplanes to arrest crack propagation, as well as regions forouter-die-perimeter microstrip routing are provided in the packagesubstrate. Additionally, a partial trench may be included in a soldermask to provide a keep out zone for epoxy fillet flow, e.g., duringunderfill.

In another example implementation, FIG. 4A illustrates a cross-sectionalview of a semiconductor package 400A including multiple die coupled withan EmIB and including microstrip routing and a metal plane toaccommodate for an epoxy fillet crack, in accordance with an embodimentof the present invention. Referring to FIG. 4A, the semiconductorpackage 400A includes a first die 402 (such as a CPU, memory chipset,etc.) and a second die 404 (such as a CPU, memory chipset, etc.). Thefirst die 402 and second die 404 are coupled to an EmIB 412 throughbumps 408 and 410 of the first die 402 and second die 404, respectively,and bond pads 406 of the silicon bridge, e.g., by thermal compressionbonding (TCB). The first die 402, second die 404, and EmIB 412 areincluded with additional routing layers 414, as depicted in FIG. 4A. Theadditional routing layers may be simple or complex and may be forcoupling to other packages or may form part or all of an organic packageor printed circuit board (PCB), etc. An epoxy-fillet material 449 isincluded between the first die 402 and the EmIB 412/structure 414interface and between the second die 404 and the EmIB 412/structure 414interface. In one embodiment, regions 401 for inclusion of discretemetal planes to arrest crack propagation, as well as regions forouter-die-perimeter microstrip routing are provided in the structure414. Additionally, a partial trench may be included in a solder mask toprovide a keep out zone for epoxy fillet flow, e.g., during underfill.In an embodiment, a silicon bridge is used and is not embedded in thepackage, but rather in an open cavity.

In another example implementation, FIG. 4B illustrates a cross-sectionalview of a semiconductor package 400B including multiple die coupled withan embedded interconnect bridge (EmIB) and including microstrip routingand a metal plane to accommodate for an epoxy fillet crack, inaccordance with an embodiment of the present invention. Referring toFIG. 4B, the semiconductor package 400B includes a first die 452 (suchas a central processing unit, CPU) and a second die 454 (such as anadditional CPU or a memory die or memory die stack, the memory die stackdepicted in FIG. 4B). The first die 452 and second die 454 are coupledto an EmIB 456 through bumps 458 and 460 of the first die 452 and seconddie 454, respectively, e.g., by thermal compression bonding (TCB). TheEmIB 456 is embedded in a substrate (e.g., flexible organic substrate)or board (such as epoxy PCB material) material 470, as depicted in FIG.4B. An epoxy fillet material 499 is included between the first die 452and the EmIB 456/substrate 470 interface and between the second die 454and the EmIB 456/substrate 470 interface. In one embodiment, regions 451for inclusion of discrete metal planes to arrest crack propagation, aswell as regions for outer-die-perimeter microstrip routing are providedin the substrate 470. Additionally, a partial trench may be included ina solder mask to provide a keep out zone for epoxy fillet flow, e.g.,during underfill.

Embodiments of the present invention may also be applicable for aninterposer structure. For example, FIG. 5 illustrates a cross-sectionalview of a semiconductor package 500 including multiple die coupled withan interposer and including microstrip routing and a metal plane toaccommodate for an epoxy fillet crack, in accordance with an embodimentof the present invention. Referring to FIG. 5, the semiconductor package500 includes a first die 502 and a second die 504. The first die 502 andsecond die 504 are coupled to an interposer 506, such as a siliconinterposer. The first die 502 and second die 504 are coupled to theinterposer 506 through bumps 508 and 510 of the first die 502 and seconddie 504, respectively, and bond pads 512 of the interposer 506, e.g., bythermal compression bonding (TCB). The interposer 506 couples the firstdie 502 and second die 504 with an organic package 520. The organicpackage 520 may include its own routing layers, as depicted in FIG. 5.Coupling through interposer 506 may be achieved by use of throughsilicon vias (TSVs) 530, as is also depicted in FIG. 5. In anembodiment, as depicted, possible locations for including an epoxyfillet material 597, 598 or 598 include between the first die 502 andinterposer 506, between the second die 504 and interposer 506, andbetween the interposer 506 and package 520. In one embodiment, regions501 for inclusion of discrete metal planes to arrest crack propagationfrom the interposer 506, as well as regions forouter-interposer-perimeter microstrip routing are provided in theorganic package 520. Additionally, a partial trench may be included in asolder mask to provide a keep out zone for epoxy fillet flow, e.g.,during underfill. It is to be understood that glass or other materialmay be used in place of silicon for an interposer structure.

In another aspect, various 3D integrated circuit packages withthrough-mold first level interconnects and including an epoxy filletmaterial are described, in accordance with embodiments of the presentinvention.

In a first example, referring to FIG. 6, a semiconductor package 600includes a substrate 602. A bottom semiconductor die 604 has an activeside 606 with a surface area. The bottom semiconductor die 604 iscoupled to the substrate 602 with the active side 606 distal from thesubstrate 602. A top semiconductor die 608 has an active side 610 with asurface area larger than the surface area of the bottom semiconductordie 604. The top semiconductor die 608 is coupled to the substrate 602with the active side 610 proximate to the substrate 602. The active side606 of the bottom semiconductor die 604 is facing and conductivelycoupled to the active side 610 of the top semiconductor die 608 by dieto die interconnect structures 612 (e.g., composed of soldered bumpsfrom each of the die). The top semiconductor die 608 is conductivelycoupled to the substrate 602 by first level interconnects 614 thatbypass the bottom semiconductor die 604. The top semiconductor die 608is further conductively coupled to the substrate 602 by a plurality ofbumps 620 (e.g., tall copper bumps) that extend from the active side 610of the top semiconductor die 608 and adjacent to the bottomsemiconductor die 604. The plurality of bumps 620 is coupled to thefirst level interconnects 614. In an embodiment, the bottomsemiconductor die 604 and the plurality of bumps 620 are housed in amolding layer 616, as depicted in FIG. 6. In an embodiment, the topsemiconductor die 608 and the bottom semiconductor die 604 are furthercoupled to the substrate 602 by an epoxy fillet material 618, as is alsodepicted in FIG. 6. In one embodiment, regions 601 for inclusion ofdiscrete metal planes to arrest crack propagation, as well as regionsfor outer-die-perimeter microstrip routing are provided in the substrate602. Additionally, a partial trench may be included in a solder mask toprovide a keep out zone for epoxy fillet flow, e.g., during underfill.

In an embodiment, the top semiconductor die 608 is configured to providepower to the bottom semiconductor die 604. In an embodiment, the topsemiconductor die 608 is configured to facilitate communication betweenthe bottom semiconductor die 604 and the substrate 604, e.g., throughrouting in the substrate 608. In an embodiment, the bottom semiconductordie 604 has no through silicon vias (TSVs). Thus, connection between thebottom die 604 and substrate 602 is achieved indirectly throughinterconnect lines on the top die 608 as well as the FLI bumps 614. Itis to be understood, however, that, in an alternative embodiment, abottom die may be connected directly by using TSV on the bottom die.

Thus, in reference to FIG. 6, for a 3D IC with through-mold FLI, bottomand top active die are stacked face-to-face. No TSV may be necessary toachieve such 3D IC stacking FLI copper bumps are embedded in a moldinglayer. The top and bottom die have a common interface underfilled by themolding compound. Fabrication-wise, the final 3D IC stacked die withthrough mold first level interconnect (FLI) is attached to a packagesubstrate, under-filled, and subsequently assembled.

One or both of the semiconductor die 604 or 608 may be formed from asemiconductor substrate, such as a single crystalline silicon substrate.Other materials, such as, but not limited to, group III-V material andgermanium or silicon germanium material substrates may also beconsidered. The active side (606 or 610, respectively) of thesemiconductor die 604 or 608 may be the side upon which semiconductordevices are formed. In an embodiment, the active side 606 or 610 of thesemiconductor die 604 or 608, respectively, includes a plurality ofsemiconductor devices, such as but not limited to transistors,capacitors and resistors interconnected together by a dieinterconnection structure into functional circuits to thereby form anintegrated circuit. As will be understood to those skilled in the art,the device side of the semiconductor die includes an active portion withintegrated circuitry and interconnections. The semiconductor die may beany appropriate integrated circuit device including but not limited to amicroprocessor (single or multi-core), a memory device, a chipset, agraphics device, an application specific integrated circuit according toseveral different embodiments.

Stacked die apparatus 600 may be particularly suitable for packaging amemory die with a logic die. For example, in an embodiment, one of die604 or 608 is a memory die. The other die is a logic die. In anembodiment of the present invention, the memory die is a memory device,such as but not limited to a static random access memory (SRAM), adynamic access memory (DRAM), a nonvolatile memory (NVM) and the logicdie is a logic device, such as but not limited to a microprocessor and adigital signal processor.

In accordance with an embodiment of the present invention, one or moreof die interconnect structures 612, plurality of bumps 620, or firstlevel interconnects 614 is composed of an array of metal bumps. In oneembodiment, each metal bump is composed of a metal such as, but notlimited to, copper, gold, or nickel. Substrate 902 may be a flexiblesubstrate or a rigid substrate, depending upon the specific application.In an embodiment, substrate 602 has a plurality of electrical tracesdisposed therein. In an embodiment, an external contact layer is alsoformed. In one embodiment, the external contact layer includes a ballgrid array (BGA). In other embodiments, the external contact layerincludes an array such as, but not limited to, a land grid array (LGA)or an array of pins (PGA).

With respect to molding layer 616, several options may be used tofabricate the layer. In an embodiment, an FLI bump and bottom-dieover-mold approach is used. In one embodiment, the over-mold layer issubsequently grinded back to expose the FLI bumps. In one embodiment,grind back is performed close to the bump (e.g., copper bump) and thenlaser ablation is used to open the copper bumps. Subsequently, solderpaste print or micro-ball attach is performed onto the copper bumps. Inone embodiment, directly laser open of the copper bumps is performedwithout any grind back. A solder operation may similarly be performed asabove. In another embodiment, bump and bottom die molding are exposedwith a polymer film above the FLI bumps and bottom die. No bump exposureis needed; however, cleaning of the FLI Cu bump may be needed by plasma,or laser, etc. In another embodiment, transfer or compression mold isused. In another embodiment, capillary underfill layer formation isextended to cover the FLI bumps in instead of conventional molding. Themolding layer 616 may be composed of a non-conductive material. In oneembodiment, the molding layer 616 is composed of a material such as, butnot limited to, a plastic or an epoxy resin composed of silica fillers.

In a second example, referring to FIG. 7, a semiconductor package 700includes a substrate 702. A bottom semiconductor die 704 has an activeside 706 with a surface area. The bottom semiconductor die 704 iscoupled to the substrate 702 with the active side 706 distal from thesubstrate 702. A top semiconductor die 708 has an active side 710 with asurface area larger than the surface area of the bottom semiconductordie 704. The top semiconductor die 708 is coupled to the substrate 702with the active side 710 proximate to the substrate 702. The active side706 of the bottom semiconductor die 704 is facing and conductivelycoupled to the active side 710 of the top semiconductor die 708 by dieto die interconnect structures 712. The top semiconductor die 708 isconductively coupled to the substrate 702 by first level interconnects714 that bypass the bottom semiconductor die 704. The top semiconductordie 708 is further conductively coupled to the substrate 702 by aplurality of bumps 720 that extend from the active side 710 of the topsemiconductor die 708, and at least partially adjacent to the bottomsemiconductor die 704, to a plurality of solder balls 722. The pluralityof solder balls 722 is coupled to the first level interconnects 714. Inan embodiment, the bottom semiconductor die 704, the plurality of bumps720, and the plurality of solder balls 722 are housed in a molding layer716, as depicted in FIG. 7. In an embodiment, the top semiconductor die708 and the bottom semiconductor die 704 are further coupled to thesubstrate 702 by an epoxy fillet material 718, as is also depicted inFIG. 7. In one embodiment, regions 701 for inclusion of discrete metalplanes to arrest crack propagation, as well as regions forouter-die-perimeter microstrip routing are provided in the substrate702. Additionally, a partial trench may be included in a solder mask toprovide a keep out zone for epoxy fillet flow, e.g., during underfill.

Thus, in reference to FIG. 7, another approach for a 3D IC withthrough-mold FLI includes disposing solder inside a molding layer. Thesolder may be placed before molding and then exposed by grind back orlaser open. Alternatively, solder paste may be placed after laseropening through copper bumps. The characteristics and configurations ofthe packaged die and the materials of package 700 may be the same orsimilar to those described above for package 600. In an embodiment, thesolder balls 722 are composed of lead or are lead free, such as alloysof gold and tin solder or silver and tin solder.

In reference to FIGS. 6 and 7, mixed FLI bump heights may be used for atop semiconductor die. For example, in one embodiment, a mixed heightFLI bump is created by using a top-hat or a slender copper columnbumping process. Here, the first bumping mask and plating operationprovides short bump heights for both FLI and LMI. The second bumpingmask and plating operation provides only the FLI bumps as taller. It isto be understood that various combinations of copper and solder bumpingmay be performed for FLI, as shown FIGS. 6 and 7.

In another aspect of the present invention, coreless substrates withembedded stacked through-silicon via die are contemplated. For example,a semiconductor die with C4 solder ball connections may be packaged in aBumpless Build-Up Layer or BBUL processor packaging technology. Such aprocess is bumpless since it does not use the usual tiny solder bumps toattach the silicon die to the processor package wires. It has build-uplayers since it is grown or built-up around the silicon die.Additionally, some semiconductor packages now use a coreless substrate,which does not include the thick resin core layer commonly found inconventional substrates. In an embodiment, as part of the BBUL process,electrically conductive vias and routing layers are formed above theactive side of a semiconductor die using a semi-additive process (SAP)to complete remaining layers. In an embodiment, an external contactlayer is formed. In one embodiment, an array of external conductivecontacts is a ball grid array (BGA). In other embodiments, the array ofexternal conductive contacts is an array such as, but not limited to, aland grid array (LGA) or an array of pins (PGA). In an embodiment, alarge die is packaged through a BBUL process. At an interface of theBBUL package and a receiving substrate, an epoxy fillet material may beused for underfill. In one such embodiment, discrete metal planes areprovided in the receiving substrate to arrest crack propagation. Aswell, outer-die-perimeter microstrip routing is provided in thereceiving substrate. Additionally, a partial trench may be included in asolder mask to provide a keep out zone for epoxy fillet flow, e.g.,during underfill.

FIG. 8 is a schematic of a computer system 800, in accordance with anembodiment of the present invention. The computer system 800 (alsoreferred to as the electronic system 800) as depicted can embodyreliable microstrip routing for dense multi-chip-package interconnectsaccording to any of the several disclosed embodiments and theirequivalents as set forth in this disclosure. The computer system 800 maybe a mobile device such as a netbook computer. The computer system 800may be a mobile device such as a wireless smart phone. The computersystem 800 may be a desktop computer. The computer system 800 may be ahand-held reader. The computer system 800 may be a server system. Thecomputer system 800 may be a supercomputer or high-performance computingsystem.

In an embodiment, the electronic system 800 is a computer system thatincludes a system bus 820 to electrically couple the various componentsof the electronic system 800. The system bus 820 is a single bus or anycombination of busses according to various embodiments. The electronicsystem 800 includes a voltage source 830 that provides power to theintegrated circuit 810. In some embodiments, the voltage source 830supplies current to the integrated circuit 810 through the system bus820.

The integrated circuit 810 is electrically coupled to the system bus 820and includes any circuit, or combination of circuits according to anembodiment. In an embodiment, the integrated circuit 810 includes aprocessor 812 that can be of any type. As used herein, the processor 812may mean any type of circuit such as, but not limited to, amicroprocessor, a microcontroller, a graphics processor, a digitalsignal processor, or another processor. In an embodiment, the processor812 includes, or is coupled with, reliable microstrip routing for densemulti-chip-package interconnects, as disclosed herein. In an embodiment,SRAM embodiments are found in memory caches of the processor. Othertypes of circuits that can be included in the integrated circuit 810 area custom circuit or an application-specific integrated circuit (ASIC),such as a communications circuit 814 for use in wireless devices such ascellular telephones, smart phones, pagers, portable computers, two-wayradios, and similar electronic systems, or a communications circuit forservers. In an embodiment, the integrated circuit 810 includes on-diememory 816 such as static random-access memory (SRAM). In an embodiment,the integrated circuit 810 includes embedded on-die memory 816 such asembedded dynamic random-access memory (eDRAM).

In an embodiment, the integrated circuit 810 is complemented with asubsequent integrated circuit 811. Useful embodiments include a dualprocessor 813 and a dual communications circuit 815 and dual on-diememory 817 such as SRAM. In an embodiment, the dual integrated circuit810 includes embedded on-die memory 817 such as eDRAM.

In an embodiment, the electronic system 800 also includes an externalmemory 840 that in turn may include one or more memory elements suitableto the particular application, such as a main memory 842 in the form ofRAM, one or more hard drives 844, and/or one or more drives that handleremovable media 846, such as diskettes, compact disks (CDs), digitalvariable disks (DVDs), flash memory drives, and other removable mediaknown in the art. The external memory 840 may also be embedded memory848 such as the first die in a die stack, according to an embodiment.

In an embodiment, the electronic system 800 also includes a displaydevice 850, an audio output 860. In an embodiment, the electronic system800 includes an input device such as a controller 870 that may be akeyboard, mouse, trackball, game controller, microphone,voice-recognition device, or any other input device that inputsinformation into the electronic system 800. In an embodiment, an inputdevice 870 is a camera. In an embodiment, an input device 870 is adigital sound recorder. In an embodiment, an input device 870 is acamera and a digital sound recorder.

As shown herein, the integrated circuit 810 can be implemented in anumber of different embodiments, including reliable microstrip routingfor dense multi-chip-package interconnects according to any of theseveral disclosed embodiments and their equivalents, an electronicsystem, a computer system, one or more methods of fabricating anintegrated circuit, and one or more methods of fabricating an electronicassembly that includes reliable microstrip routing for densemulti-chip-package interconnects according to any of the severaldisclosed embodiments as set forth herein in the various embodiments andtheir art-recognized equivalents. The elements, materials, geometries,dimensions, and sequence of operations can all be varied to suitparticular I/O coupling requirements including array contact count,array contact configuration for a microelectronic die embedded in aprocessor mounting substrate according to any of the several disclosedreliable microstrip routing for dense multi-chip-package interconnectsembodiments and their equivalents. A foundation substrate may beincluded, as represented by the dashed line of FIG. 8. Passive devicesmay also be included, as is also depicted in FIG. 8.

Embodiments of the present invention include reliable microstrip routingarrangements for electronics components.

In an embodiment, a semiconductor apparatus includes a semiconductor diehaving a surface with an integrated circuit thereon coupled to contactpads of an uppermost metallization layer of a semiconductor packagesubstrate by a plurality of conductive contacts. A plurality of discretemetal planes is disposed at the uppermost metallization layer of thesemiconductor package substrate, each metal plane located, from a planview perspective, at a corner of a perimeter of the semiconductor die.Microstrip routing is disposed at the uppermost metallization layer ofthe semiconductor package substrate, from the plan view perspective,outside of the perimeter of the semiconductor die.

In one embodiment, the semiconductor apparatus further includes an epoxyfillet layer disposed between the surface of the semiconductor die andthe semiconductor package substrate and surrounding the plurality ofconductive contacts.

In one embodiment, the plurality of discrete metal planes is forarresting propagation of one or more cracks from the epoxy fillet layeror a solder resist SR layer under the epoxy fillet or a die corner.

In one embodiment, the semiconductor apparatus further includes a crackin the epoxy fillet layer, and propagation of the crack is arrested atone of the plurality of discrete metal planes.

In one embodiment, the semiconductor apparatus further includes a solderresist disposed on the uppermost metallization layer of thesemiconductor package substrate and surrounding the plurality ofconductive contacts, and the epoxy fillet layer is disposed on thesolder resist.

In one embodiment, the semiconductor apparatus further includes a trenchformed in the solder resist, from the plan view perspective, outside ofthe perimeter of the semiconductor die, the trench providing a keep outzone for the epoxy fillet layer.

In one embodiment, the trench is formed only partially into the solderresist, and, from the plan view perspective, a portion of the microstriprouting is underneath the trench.

In one embodiment, the solder resist includes a first solder resistlayer disposed on a second solder resist layer, and the trench isdisposed in the first solder resist layer but not in the second solderresist layer.

In an embodiment, a semiconductor package includes first and secondadjacent semiconductor dies. A silicon bridge structure electricallycouples the first and second semiconductor dies, and includes aplurality of layers of conductive traces disposed above a substrate, afirst pair of ground traces disposed in a first of the plurality oflayers of conductive traces, a signal trace disposed in a second of theplurality of layers of conductive traces, below the first layer, and asecond pair of ground traces disposed in a third of the plurality oflayers of conductive traces, below the first layer. The semiconductorpackage also includes a plurality of package routing layers, and thesilicon bridge structure is disposed in one of the package routinglayers. The first and second die are disposed on the plurality ofpackage routing layers, and the first die is electrically coupled to anuppermost metallization layer of the plurality of package routing layersby a plurality of conductive contacts. One or more discrete metal planesis disposed at the uppermost metallization layer, each metal planelocated, from a plan view perspective, at a corner of a perimeter of thefirst die. The semiconductor package also includes microstrip routingdisposed at the uppermost metallization layer, from the plan viewperspective, outside of the perimeter of the first die.

In one embodiment, the semiconductor package further includes an epoxyfillet layer disposed between the first die and the uppermostmetallization layer and surrounding the plurality of conductivecontacts.

In one embodiment, one or more discrete metal planes is for arrestingpropagation of one or more from the epoxy fillet layer or a solderresist SR layer under the epoxy fillet or a die corner.

In one embodiment, the semiconductor package further includes a crack inthe epoxy fillet layer, and propagation of the crack is arrested at oneof the one or more discrete metal planes.

In one embodiment, the semiconductor package further includes a solderresist disposed on the uppermost metallization layer and surrounding theplurality of conductive contacts, and the epoxy fillet layer is disposedon the solder resist.

In one embodiment, the semiconductor package further includes a trenchformed in the solder resist, from the plan view perspective, outside ofthe perimeter of the first die, the trench providing a keep out zone forthe epoxy fillet layer.

In one embodiment, the trench is formed only partially into the solderresist, and, from the plan view perspective, a portion of the microstriprouting is underneath the trench.

In one embodiment, the solder resist includes a first solder resistlayer disposed on a second solder resist layer, and the trench isdisposed in the first solder resist layer but not in the second solderresist layer.

In an embodiment, a semiconductor package includes first and secondadjacent semiconductor dies. A silicon interposer structure is disposedbelow and electrically coupling the first and second semiconductor dies.An organic package substrate is disposed below and electrically coupledto the silicon interposer structure by a plurality of conductivecontacts. The organic package substrate includes a plurality of routinglayers therein. A plurality of discrete metal planes is disposed at anuppermost metallization layer of the plurality of routing layers of theorganic package substrate, each metal plane located, from a plan viewperspective, at a corner of a perimeter of the silicon interposerstructure. Microstrip routing is disposed at the uppermost metallizationlayer of the plurality of routing layers of the organic packagesubstrate, from the plan view perspective, outside of the perimeter ofthe silicon interposer structure.

In one embodiment, the semiconductor package further includes an epoxyfillet layer disposed between the silicon interposer structure and theorganic package substrate and surrounding the plurality of conductivecontacts.

In one embodiment, the plurality of discrete metal planes is forarresting propagation of one or more from the epoxy fillet layer or asolder resist SR layer under the epoxy fillet or a die corner.

In one embodiment, the semiconductor package further includes a crack inthe epoxy fillet layer, and propagation of the crack is arrested at oneof the plurality of discrete metal planes.

In one embodiment, the semiconductor package further includes a solderresist disposed on the uppermost metallization layer and surrounding theplurality of conductive contacts, and the epoxy fillet layer is disposedon the solder resist.

In one embodiment, the semiconductor package further includes a trenchformed in the solder resist, from the plan view perspective, outside ofthe perimeter of the silicon interposer structure, the trench providinga keep out zone for the epoxy fillet layer.

In one embodiment, the trench is formed only partially into the solderresist, and, from the plan view perspective, a portion of the microstriprouting is underneath the trench.

In one embodiment, the solder resist includes a first solder resistlayer disposed on a second solder resist layer, and the trench isdisposed in the first solder resist layer but not in the second solderresist layer.

In one embodiment, the organic package substrate is electrically coupledto the silicon interposer structure by one or more through-silicon-vias(TSVs) disposed in the silicon interposer structure.

What is claimed is:
 1. A semiconductor package, comprising: first andsecond adjacent semiconductor dies; a silicon bridge structureelectrically coupling the first and second semiconductor dies, andcomprising a plurality of layers of conductive traces disposed above asubstrate, a first pair of ground traces disposed in a first of theplurality of layers of conductive traces, a signal trace disposed in asecond of the plurality of layers of conductive traces, below the firstlayer, and a second pair of ground traces disposed in a third of theplurality of layers of conductive traces, below the first layer; aplurality of package routing layers, wherein the silicon bridgestructure is disposed in one of the package routing layers, the firstand second die are disposed on the plurality of package routing layers,and the first die is electrically coupled to an uppermost metallizationlayer of the plurality of package routing layers by a plurality ofconductive contacts; one or more discrete metal planes disposed at theuppermost metallization layer, each metal plane located, from a planview perspective, at a corner of a perimeter of the first die; andmicrostrip routing disposed at the uppermost metallization layer, fromthe plan view perspective, outside of the perimeter of the first die. 2.The semiconductor package of claim 1, further comprising: an epoxyfillet layer disposed between the first die and the uppermostmetallization layer and surrounding the plurality of conductivecontacts.
 3. The semiconductor package of claim 2, wherein one or morediscrete metal planes is for arresting propagation of one or more cracksfrom the epoxy fillet layer or a solder resist SR layer under the epoxyfillet or a die corner.
 4. The semiconductor package of claim 2, furthercomprising: a crack in the epoxy fillet layer, wherein propagation ofthe crack is arrested at one of the one or more discrete metal planes.5. The semiconductor package of claim 2, further comprising: a solderresist disposed on the uppermost metallization layer and surrounding theplurality of conductive contacts, wherein the epoxy fillet layer isdisposed on the solder resist.
 6. The semiconductor package of claim 5,further comprising: a trench formed in the solder resist, from the planview perspective, outside of the perimeter of the first die, the trenchproviding a keep out zone for the epoxy fillet layer.
 7. Thesemiconductor package of claim 6, wherein the trench is formed onlypartially into the solder resist, and wherein, from the plan viewperspective, a portion of the microstrip routing is underneath thetrench.
 8. The semiconductor package of claim 7, wherein the solderresist comprises a first solder resist layer disposed on a second solderresist layer, and wherein the trench is disposed in the first solderresist layer but not in the second solder resist layer.